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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Society of Coastal and Ocean Engineers
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Journal DOI :
Korean Society of Coastal and Ocean Engineers
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Volume & Issues
Volume 26, Issue 6 - Dec 2014
Volume 26, Issue 5 - Oct 2014
Volume 26, Issue 4 - Aug 2014
Volume 26, Issue 3 - Jun 2014
Volume 26, Issue 2 - Apr 2014
Volume 26, Issue 1 - Feb 2014
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Field Monitoring Examination on Wave Energy Dissipation Effects by Submerged Artificial Reefs
Kim, Kyu-Han ; Shin, Bum-Shick ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 1, 2014, Pages 1~8
DOI : 10.9765/KSCOE.2014.26.1.1
In this study, a field monitoring on Namae beach erosion countermeasure in the east coast of Korea is conducted to verify its efficiency and effectiveness. The Namae Beach project has been carried out for six years with three years for planning and three years for actual construction. The planning phase of numerical model tests and investigations had been reported by Kim et al. (2008, 2011). The field monitoring confirms increase in the beach width after the submerged artificial reefs construction and is due to its wave energy dissipation effects. The field monitoring is performed at the seaward and landward of the countermeasures. The wave height reduction from the seaward side (depth h = 10.5 m) to the landward side (h = 3.7 m) of the reef is measured for wave transmission coefficient (Kt) analysis. The analysis shows 60% of deduction in wave energy due to the submerged artificial reefs.
Anchor Collision Simulation of Rock-berm using SPH Technique
Woo, Jinho ; Na, Won-Bae ; Yu, Jeong-Seok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 1, 2014, Pages 9~15
DOI : 10.9765/KSCOE.2014.26.1.9
It is not easy to analyze the behavior of a structural body composed of particles such as rocks using the finite element method facilitating typical element meshes because we cannot ignore the interactions among particles. In the study, we investigated the applicability of smooth particle hydrodynamics (SPH) element method for collision analysis of rock-berm by comparison with the conventional Lagrange method. As the result, SPH technique is expected to be capable of realistic simulation under collision analysis of material composed of particles.
Extreme Offshore Wind Estimation using Typhoon Simulation
Ko, Dong Hui ; Jeong, Shin Taek ; Cho, Hongyeon ; Kang, Keum Seok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 1, 2014, Pages 16~24
DOI : 10.9765/KSCOE.2014.26.1.16
Long-term measured wind data are absolutely necessary to estimate extreme offshore wind speed. However, it is almost impossible to collect offshore wind measured data. Therefore, typhoon simulation is widely used to analyze offshore wind conditions. In this paper, 74 typhoons which affected the western sea of Korea during 1978-2012(35 years) were simulated using Holland(1980) model. The results showed that 49.02 m/s maximum wind speed affected by BOLAVEN(1215) at 100 m heights of HeMOSU-1 (Herald of Meteorological and Oceanographic Special Unit - 1) was the biggest wind speed for 35 years. Meanwhile, estimated wind speeds were compared with observed data for MUIFA, BOLAVEN, SANBA at HeMOSU-1. And to estimate extreme wind speed having return periods, extreme analysis was conducted by assuming 35 annual maximum wind speed at four site(HeMOSU-1, Gunsan, Mokpo and Jeju) in western sea of the Korean Peninsular to be Gumbel distribution. As a results, extreme wind speed having 50-year return period was 50 m/s, that of 100-year was 54.92 m/s at 100 m heights, respectively. The maximum wind speed by BOLAVEN could be considered as a extreme winds having 50-year return period.
Comparative Analysis on the Design Conditions for Offshore Wind Power Structures in the Coastal Sea of Korea
Ko, Dong Hui ; Jeong, Shin Taek ; Cho, Hongyeon ; Kang, Keum Seok ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 1, 2014, Pages 25~32
DOI : 10.9765/KSCOE.2014.26.1.25
Offshore wind power structures are subject to coastal hydrodynamic loading such as wind and wave loads. A considerable number of turbines have been installed in Europe, but so far none in Korea. Interest in offshore wind energy is growing in Korea, and it is expected that projects will reach the design stage in the near future. This paper discusses the level of structural reliability implied by the design rules of ABS(2010, 2013) and IEC(2009). Metocean conditions in 4 Korean seas(Gunsan, HeMOSU 1, Mokpo, Jeju) were used in the calibrations to calculate the aerodynamic and hydrodynamic loads as well as the structural responses of the typical designs of offshore wind turbines. Due to the higher variability of the wind and wave climate in hurricane-prone areas, applying IEC strength design criteria in combination with Korea west sea conditions could result in a design with much lower reliability index than what is anticipated from a design in European waters. To achieve the same level of safety as those in European waters, application of ABS 100 year design standards are recommended. Level-1 reliability-based design suitable for the Korean sea state conditions should be introduced because the IEC standards does not consider the typhoon effects in depth and the ABS standards is a WSD design method. In addition, the design equation should be established based on the statistical characteristics of the wind and wave loads of the Korean sea areas.
Reliability Analysis Offshore Wind Turbine Support Structure Under Extreme Ocean Environmental Loads
Lee, Sang Geun ; Kim, Dong Hyawn ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 1, 2014, Pages 33~40
DOI : 10.9765/KSCOE.2014.26.1.33
Reliability analysis of jacket type offshore wind turbine (OWT) support structure under extreme ocean environmental loads was performed. Limit state function (LSF) of OWF support structure is defined by using structural dynamic response at mud-line. Then, the dynamic response is expressed as the static response multiplied by dynamic response factor (DRF). Probabilistic distribution of DRF is found from response time history under design significant wave load. Band limited beta distribution is used for internal friction angle of ground soil. Wind load is obtained in the form of thrust force from commercial code called GH_Bladed and then, applied to tower hub as random load. In a numerical example, the response surface method (RSM) is used to express LSF of jacket type support structure for 5MW OWF. Reliability index is found using first order reliability method (FORM).
Storm Surges in West Coast of Korea by Typhoon Bolaven (1215)
Seo, Seung Nam ; Kim, Sang Ik ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 1, 2014, Pages 41~48
DOI : 10.9765/KSCOE.2014.26.1.41
To analyze the surface elevation data of Typhoon Bolaven, simple analytical models are employed to investigate major causes of the storm surges in the west coast of Korea. Although the simple models cannot reproduce the storm surges by Typhoon Bolaven accurately, they are able to provide sufficient evidence of physical processes involved in the storm surges. Surges in islands located at deeper water were mainly driven by typhoon low pressure rather than associated winds. In contrast, bigger storm surge heights more than 1m were recorded in shallow coastal areas during low tide, which were dominantly produced by typhoon winds.
Numerical Simulation on Seabed-Structure Dynamic Responses due to the Interaction between Waves, Seabed and Coastal Structure
Lee, Kwang-Ho ; Baek, Dong-Jin ; Kim, Do-Sam ; Kim, Tae-Hyung ; Bae, Ki-Seong ;
Journal of Korean Society of Coastal and Ocean Engineers, volume 26, issue 1, 2014, Pages 49~64
DOI : 10.9765/KSCOE.2014.26.1.49
Seabed beneath and near the coastal structures may undergo large excess pore water pressure composed of oscillatory and residual components in the case of long durations of high wave loading. This excess pore water pressure may reduce effective stress and, consequently, the seabed may liquefy. If the liquefaction occurs in the seabed, the structure may sink, overturn, and eventually fail. Especially, the seabed liquefaction behavior beneath a gravity-based structure under wave loading should be evaluated and considered for design purpose. In this study, to evaluate the liquefaction potential on the seabed, numerical analysis was conducted using 2-dimensional numerical wave tank. The 2-dimensional numerical wave tank was expanded to account for irregular wave fields, and to calculate the dynamic wave pressure and water particle velocity acting on the seabed and the surface boundary of the structure. The simulation results of the wave pressure and the shear stress induced by water particle velocity were used as inputs to a FLIP(Finite element analysis LIquefaction Program). Then, the FLIP evaluated the time and spatial variations in excess pore water pressure, effective stress and liquefaction potential in the seabed. Additionally, the deformation of the seabed and the displacement of the structure as a function of time were quantitatively evaluated. From the analysis, when the shear stress was considered, the liquefaction at the seabed in front of the structure was identified. Since the liquefied seabed particles have no resistance force, scour can possibly occur on the seabed. Therefore, the strength decrease of the seabed at the front of the structure due to high wave loading for the longer period of time such as a storm can increase the structural motion and consequently influence the stability of the structure.